Lubricating bearing surface



Patented Feb. 7, 1939 UNITED STATES LUBRICATING BEARING SURFACE Troy LeeCantrell and James Otho Turner, Lansdowne, Pa., assignors to Gulf OilCorporation, Pittsburgh, Pa, a. corporation of Pennsylvania No Drawing.Application June 5, 1936, Serial No. 83,760

1 Claim.

This invention relates to improved methods of lubricating bearingsurfaces in internal combustion engines when subjected to conditions ofoperation which comprises maintaining between bearing surfaces, one ofwhich is an alloy formed chiefly of a metal of the class consisting ofcad mium and copper, a mineral lubricating oil which initially producesan efiective lubricating action but which would normally tend to corrodethe aforesaid alloy and maintaining the efiectiveness of the lubricatingoil by incorporating isoeugenol in a small but sufficient proportionsubstantially to retard the corrosion; all as more fully hereinafter setforth and as claimed.

Recent developments in the design of mechanical equipment for generatingand transmitting conditions imposed by modern engineering de-' sign,these new alloy bearingsarecommonly subjected to more severe operatingconditions than were usual in the older art; to higher bearing loads,higher rubbing speeds and higher temperatures of opera tion. It is foundthat in actual use under these conditions there often develops seriousdestructive action on the bearing surface by mineral lubricating oils,even by those standard commercial oils giving particularly good resultswith the older bearing metals under the earlier operating conditions.The destruction of the bearing metal probably results from action ofdeterioration products developed in the oil. An object achieved in thepresent invention is the production of lubricating oils improved forthese newer conditions of use and which are characterized by reductionor elimination of destructive action on the newer bearing metals bydeterioration products in the oil.

We have discovered that isoeugenol, incorporated with the oil, iscapable of achieving the objects of the present invention. By addingsmall amounts of isoeugenol, say 0.05 to 0.40 per cent by weight to themineral oil or lubricant, we obtain improved lubricating compositionswhich satisfactorily lubricate the said alloy bearings. Incorporated inmineral oil, isoeugenol retards destruction of the bearing metal. Theamounts of isoeugenol necessary to obtain this improvement are such thatthe initial properties of the oil, such as viscosity, gravity, color,etc., are not substantially altered. Thus, by the present invention,certain properties of the lubricant are improved without sacrificing theother desirable properties of the lubricating oil.

Isoeugenol is a well known chemical compound, being industriallyproduced in quantity in the manufacture of vanillin. It isl-propenyll-hydroxy-3-methoxy-benzene, having the formula It is a clear,viscous liquid boiling at 267.5 C. and having a specific gravity of1.091 B. at 15/15 C. Isoeugenol is completely soluble in alcohol andether, but is only slightly soluble in Water.

Isoeugenol is soluble in and miscible with mineral oils and the like insuflicient proportion to efiect our desired improvement in the oil. bythe present invention, we obtain improved mineral oils and petroleum oillubricantssuitable for lubricating alloy bearings under. a wide range ofservice conditions; even when there is a free circulation of air.

The isoeugenol may be incorporated withthe mineral oil or lubricatingbase in any suitable manner. It may be dissolved in the oil by simplymixing it with the oil and slightly warming with agitation to obtainuniform lubricants. Warming to temperatures between F. and 180 F. issuflicient. lubricating oils this Warming is advantageous since theheating lowers the viscosity of the oil and so facilitates the blending.To agitate the mixture, various mechanical agitators may be employed.Also, a current of air may be passed through the mixture to obtainthorough mixin and blending. The isoeugenol may be first dissolved in asuitable lubricating oil to forma master batch which is subsequentlyblended with more lubricating oil to give a range of lubricatingcompositions as desired. Likewise the compounded lubricant may beconverted into thickened compositions or greases in any of the usualways. The isoeugenol may be directly added to metal soap grease or othercompounded lubricant in which a petroleum oil is the lubricating base.

In the practice of the present invention, any suitable minerallubricating oil base may be employed, either heavy or light oil. It isbest to select a good grade of mineral lubricating oil which hassuitable initial properties for the particular. lubrication requirement.The addition of isoeugenol produces the additional desiredcharacteristic of restraining the destructiveness of oil deteriorationproducts toward the newer Thus,

With the heavier and more viscous alloy bearing metals, etc. That is,petroleum oils and lubricants of the usual grades may be employed inpracticing this invention. The oils falling within the well known S. A.E. classifications are among those which can advantageously be improvedby our invention. Likewise, special lubricants such as obtained byblending certain non-petroleum oils with mineral oil may be improved bythe addition of isoeugenol.

The corrosion and pitting of bearing metals by particular oils underdrastic service conditions may be readily observed by visual inspection,but a special laboratory test is necessary to readily and quicklydetermine the destructive action of oil deterioration products on astandard comparable and reproducible basis and to readily evaluatecommercial lubricants for such alloy bearings, We have devised asatisfactory accelerated test procedure which is as follows:

An alloy bearing shell of certain commonly used standard dimensions issubmerged in 300 cc. of the oil or oil composition in a 400 cc. Pyrexbeaker and heated in a thermostatically controlled oil bath to 175 C.(347 F.) and air, at the rate of 2000 cc. per hour, is bubbled throughthe oil in contact with the bearing shell. At the end of 48 and 96hours, the loss of weight and the condition of the bearing shell aredetermined. This test will hereinafter be referred to as our standardlaboratory test.

In determining the loss in weight the bearing shell is washed free ofoil and dried before Weighing.

When determining the effectiveness of various improvement agents theusual procedure is to run a blank test simultaneously with the oilcomposition being tested, employing for that purpose a sample of theuntreated oil.

In such tests it is advantageous to employ commercial bearing shells.These shells comprise a suitable metal backing faced with the alloybearing metal, In the above test, the air is bubbled against the alloybearing face. In this way, the actual bearing face is subjected tosevere deteriorative conditions. By comparison of the results of suchtests with actual service tests, we have found them to be in substantialagreement as to ,the suitability of particular lubricants. v

In testing our lubricants, we have employed, among others, bearings ofthe following approximate composition:

1. Cadmium-silver alloy, 7610.

Metal Percent Cadmium 98 Silver 1 Copper 1 2. Lead-copper alloy, 9020CA.

Metal Percent Such alloys are used in the tests of illustrative improvedlubricants given post. In such tests the loss in weight, while notextremely high when expressed as per cent loss, is nevertheless verysignificant, as the bearing shells used have an alloy facing of only.008 inch to .012 inch thickness on a highly resistant backing and theobserved losses in the reported tests often represent a loss of theorder of ten per cent of the alloy facing.

The specific examples and tests given post are illustrative of detailembodiments of the present invention.

The specific examples and tests given post are illustrative of detailembodiments of the present invention,

Example 1.-Into a suitable vessel there are introduced 1000 gallons(7200 lbs.) of Pennsylvania motor oil S. A. E. grade and the oil warmedto 160 F. Then 7.2 pounds of isoeugenol (0.10 per cent by weight on theoil) are gradually added and the mixture agitated until a uniform blendis obtained; about 1 hour being required. The improved motor oil is thencooled and packaged into suitable containers. In agitating the mixture,ordinary mechanical agitators may be employed or a current of air may bepassed through the warm mixture to produce uniform blending.

The properties of the original and improved motor oil are as follows:

Table A Improved Original oil lubricant Gravity: API Viscosity, SUV:

210 F Flash, 0.0.: T. Fire 0. (1.: F Pour: F 0 0 Color: NPA Carbonresidue: Percent Neutralization No Copper strip test Nil i SatisfactorySatisfactory Table B Improved Bearing shell weightlubricant Original oilGrams Before test After test Total change Comment Bearing appearance(after test)- Insignificant No change Badly etched and pitted .S. A. E.20 grade motor oil in lieu of the particular materials in Example 1,another improved motor oil is obtained It is likewise satisfactory forlubricating these alloy bearings without substantial corrosion. Whenlikewise subjected to the standard test the following results wereobtained:

Table 0' Bearing shell weight- Original oil fi g gxg Grams Grams Beforetest 26. 7291 36. 0561 After test 26. 4205 36. 0560 Total change 0.3086-0 0001 Comment Significant loss Insignificant loss Bearing appearance(after Badly etched and N 0 change test). pitted The above examples arebut illustrative embodiments of the present invention and in practiceother embodiments may be used. That is, the percentage of isoeugenoladded to the lubricant to improve it may be varied, as indicated,according to the particular properties desired in the final lubricantand the lubricating base used. Likewise, the lubricating base itself maybe selected according to the type. of the final lubricant to beproduced. For instance, any of the usual greases or the usual blends ofmineral and blown fatty oils may bejemployed as the lubricating base inmaking lubricants of those types. When incorporating the isoeugenol in agrease composition or like thickened lubricants, mechanical agitatorsrather than a current of air are employed to obtain uniform mixing andblending. That is, the isoeugenol and the grease may be compounded inthe usual mixtures such as blade mixers equipped with heating jackets.However, in making such greases the isoeugenol may be first incorporatedwith the oil base according to the procedure of Example 1 and then themetal soap or other thickened agent added .to the improved oil, in theordinary way to produce the desired grease composition. In other words,the improved mineral oil of the present invention may be used in lieu ofthe ordinary oils in making spcecial lubricating compositions such asgreases, e

as stated ante, the incorporation of isoeugenol with the lubricatingbase produces several improvements in the final lubricant withoutdeleteriously afiecting the desirable properties. While the exactreasons for the improvements obtained are not fully known, we aresatisfied with observing and utilizing the actual improvements obtainedby adding and incorporating isoeugenol with commercial lubricants.

Isoeugenol alone is a highly effective improvement agent for minerallubricating oil, and we also find it useful as an assistant to numerousother so-called improvement agents, and its use in conjunction withother so-called improvement agents which have-unpleasant odors isespecially desirable because the pleasant odor of isoeugenol tends toscreen any unpleasant odors which may be present.

The use as improvement agents of materials which contain either sulfuror chlorin or both in their chemical constitution is known. But bothsulfur and chlorin, present in this matter, are found undesirable undercertain conditions of use, and our use of.isoeugenol as an improvementagent for mineral lubricating .oils completely avoids the undesirableeffects just referred to.

The addition of isoeugenol to lubricating oil not only has utility, asdescribed at length herein, but it also imparts to the oil a pleasantcharacteristic non-petroleum odor.

What we claim is: I

A method of lubricating bearing surfaces in internal combustion engineswhen subjected to conditions of operation which-comprises maintainingbetween bearing surfaces, one of which is an alloy formed chiefly of ametal selected from the class consisting of cadmium and copper, a filmof lubricating oil which initially produces an efiective lubricatingaction but which would normally tend to corrode the aforesaid alloy, andmaintaining the effectiveness of the lubricating oil by incorporatingtherein isoeugenol in a small but suflicient proportion substantially toretard the corrosion.

TROY LEE CANTREIL. JAMES O'I'HO TURNER.

